A report about marine diesel engines

2. • A diesel engine is an internal combustion
engine.
• It uses the heat of compression to initiate
ignition to burn the fuel that has been
injected into the combustion chamber.
• The engine was developed by German
inventor Rudolf Diesel in 1893.
• The engine works on the principle of
diesel cycle

3. The Diesel cycle is the thermodynamic cycle
which approximates the pressure and volume
of the combustion chamber of the Diesel
engine, invented by Rudolph Diesel in 1897. It
is assumed to have constant pressure during
the first part of the "combustion" phase.

4. enginesThe slow speed DieselSlow speed :-1
are applied in large vessels whith large engine
rooms.
Slow- speed Diesel engines consume Heavy
Fuel Oil, which is an inexpensive fuel.
2-medium speed: Are used in large electrical
generators, ship propulsion and mechanical
drive applications such as large compresors or
pumps.
3-High speed: Are used in small, highly
manoeuvrable vessels.
The rated capacity of such an engine is very
high, but so is its fuel consumption.

5. 1- Two- stroke engine:
The two stroke internal combustion engine
completes the thermodynamic cycle in two
movements of the piston. This increased
efficiency is accomplished by using the
beginning of the compression stroke and the
end of the combustion stroke to
simultaneously

6. 2- four- stroke engines: Today internal
combustion engines in cars, trucks,
motorcycles, aircraft, construction machinery
and many others, most commonly use a four
stroke engine
-Four strokes involve:
1.INTAKE stroke: Piston descends from the
TDC to BDC increasing the volume of the
cylinder. Air is forced into the cylinder
through the intake port.
2.COMPRESSION stroke: with both valves
closed, the piston returns to TDC
compressing the air into the combustion
chamber of the cylinder head.
Temperature gets increased to hundred
degrees.

7. 3.POWER stroke: While the piston is close
to TDC, the compressed fuel injected into
a diesel engine ignites due to the heat
generated in the air during the
compression stroke.
4.EXHAUST stroke: Here, the piston once
again returns to top dead centre while the
exhaust valve is open. The spent fuel-air
mixture is expelled.

8. 1.CRANKSHAFT
– Singular costliest item in diesel
engine.
– Medium of transforming reciprocating
motion to rotary motion.
– Balance weights can be either bolted
up or welded.

9. 2.CAM SHAFT
– Performs the vital role of opening &
closing inlet & exhaust valves.
– Allow timely injection of fuel inside
the cylinder.
– Usually 3 cams for each cylinder-
 2 outer cams for exhaust & inlet valves
 1 central cam for fuel injection

10. 3.CYLINDER HEAD
– CH is held on the cylinder liners by 7
hold down studs.
– Subjected to high shock stress &
combustion temperature at the lower
face.
– Complicated casting where cooling
passages are cored for holding water.
– Space had been provided for passage
of inlet air & exhaust gases.
– Space for fuel injection nozzles, valve
guides & valve seat.

11. • Diesel Engine relies upon compression
ignition.
• Compression ratio lies b/w 16:1 and 25:1.
Temp. increases to 700C to 900C.
• Piston approaches TDC, fuel is injected.
• Ignition instantly occurs, causing a rapid
increase in cylinder temperature &
pressure.
• Piston is driven downward with great
force, pushing on the connecting rod &
turning the crankshaft.
• Exhaust gases are expelled then.